基于单片机的人体脉搏检测系统设计

基于单片机的人体脉搏检测系统设计

摘要

脉搏波所呈现出来的形态、强度、速率和节律等方面的综合信息，能反映出人体心血管系统中许多生理疾病的血流特征。本课题是人体脉搏测量仪的设计。由于脉搏信号的特殊性，在设计时必须要注意实现测量的准确。该系统的重点就在于要求实现测量的简便化和精确化。系统测量出人体一分钟的脉搏，并且保证误差在2次以内。本系统以89S51单片机作为中心，通过使用单片机来实现系统最核心的计算脉搏功能。在信号的前端处理上，使用压电陶瓷片采集人体脉搏信号，然后经过AD620放大，施密特触发器整形，低通滤波器滤波等一系列操作，将脉搏信号转换为同频率的脉冲信号输入到单片机内，并利用单片机对其进行计数。计数的方法是利用单片机的计时器，然后由该周期计算出频率，继而就可以求出一分钟的脉搏数。计数结果将最终送至液晶屏1602来进行显示。虽然压电陶瓷片的性能并非很好，在信号的采集上不能实现非常精确的采集，但是它的价格低廉，并且在经过系统的信号调理电路后，也能比较满意的实现我们所要实现的目标。系统运行中能显示脉搏次数和时间，系统停止运行时，能够显示总的脉搏次数和时间。本文首先描述本设计的整体思路，然后介绍各个部分设计中的细节问题，最后提出一些完善本设计的改进意见。

关键字：脉搏测量；压电陶瓷片；液晶显示屏；单片机

THE DESIGN OF HUMAN PLUSE DETECTION SYSTEM

BASED ON MCU

ABSTRACT

The shape, intensity, speed, and rhythm of pulse signals mostly reflect the physical and pathological characters of heart-blood system in human bodies. This topic is a design of body pulse measuring instrument. Because of the specificity of the pulse signal, the design must pay attention to achieve an accurate measurement.The point of this design is the simple and precise of the measurement.We need to measure the pulse of the human body in one minute,and to ensure that the error in less than 2 times..The whole system is center on single-chip microcomputer 89s51,using the signle-chip to achieve the system core function of counting pulse.In the front-end of the signal, we use piezoelectric ceramics to collect the signal of the human body pulse.And then,after after amplification of the AD620, shaping of the 555, filtering of the low-pass filter and other operations,the signal will be converted to the pulse signal with the same frequency,and this signal will be input to the single-ship.The single-ship will count to this.The method of counting is using the timer of the single-ship,and then use the cycle,get the frequency,by the frequency,we can get the number of the one-minute pulse. The final result of the count will display in the 1602 LCD screen.Although the performance of the piezoelectric ceramics is not very good,in the signal collection.it can’t do it very precise.But its price is very low,and after the signal conditioning circuit of the system,the signal can be quite satisfactory to achieve our objectives. At the beginning of the paper, the integral notion of the device design is brought out. Afterwards, the detail information of each part is narrated. At last part, some suggestions for improving the device are provided.

Key words:Pulse measurement; piezoelectric ceramics; LCD; single-ship

目录

1 绪论 (1)

1.1课题背景及目的 (1)

1.2国内外研究状况及发展趋势 (2)

1.3课题研究难点 (3)

1.3.1 抗干扰 (3)

1.3.2 低噪声、低漂移 (3)

1.4课题主要研究内容 (4)

2 系统总体设计 (5)

2.1系统硬件电路设计方案 (6)

2.1.1传感器的选择 (6)

2.1.2 单片机的选择 (8)

2.1.3 信号调理电路的选择 (9)

2.2系统软件设计方案 (10)

2.2.1 脉搏波动频率测量方案的选择 (10)

2.2.2 单片机工作方式的选择 (10)

2.2.3 显示电路方案的选择 (11)

3 系统硬件设计 (11)

3.1一级放大电路的设计 (12)

3.2二阶滤波器电路的设计 (14)

3.3第二级放大电路的设计 (17)

3.4整形电路 (18)

3.5定时计数电路的设计 (21)

3.6显示电路的设计 (22)

4 系统软件设计 (25)